I've just read some of the interesting analysis about Caislan Drom an Oir - Castle of Dromore.
I would like to submit the following .... The Gaelic text leans towards "Munster irish", but that may not a definitive factor in locating the precise area of origin. That the tune or air is Irish in origin is of little doubt, given it's structure etc..etc... As most people know, many old English, Scots and Irish tunes and airs, were used ny later writers from both sides of the pond ! I first heard this sung back in 1971, by an old, native Gaelic speaker (Nell Lynch - nee Carthy) of Ballingeary, who was born 1896 ( a relative ). She could not speak English until about 7 or 8, and learned it as a child in Gaelic, from her father, Tim Carthy, who died circa 1904 or 1905 .....he was born 1838-39, so we have a Gaelic version, immersed in the MUSCRAI song traditon of West Cork predating the late 1800's ... ??? Interesting stuff !!